What Is a Multiple Pregnancy?

A pregnancy has two or more fetuses in the uterine cavity at the same time, which is called multiple pregnancy. The incidence of multiple pregnancy is related to factors such as race, age and genetics.

Basic Information

English name: multiple pregnancy
Visiting department: Obstetrics and Gynecology

Common causes: Genetic factors; age and parity; endogenous gonadotropins; application of ovulation-promoting drugs, etc.
Common symptoms: Two or more fetuses in one pregnancy

Causes of multiple pregnancy

Genetic factor

Multiple pregnancy has a family sexual orientation. The incidence of multiple births increases in those who have multiple births in a couple's family. Monozygotic twins are not genetically related. Diploid twins have a clear genetic history. If the woman is one of the twins, the probability of giving birth is higher than that of the husband's twin, suggesting that the mother's genotype effect is greater than that of the father.

2. Age and parity

As the maternal age and parity increase, the incidence of multiple births may increase, but this effect is not obvious.

3. Endogenous gonadotropin

The occurrence of spontaneous dizygotic twins is associated with higher levels of follicle-stimulating hormone (FSH) in the body.

4. Application of ovulation-promoting drugs

Multiple pregnancy is the main complication of drug-induced ovulation, which is related to individual response differences and excessive doses. During the application of human menopausal gonadotropin (HMG) treatment, ovarian hyperstimulation is prone to cause multiple ovulation, and the chance of twins will increase by 20% to 40%.

Clinical manifestations of multiple pregnancy

Twin pregnancy usually has a family history, pre-pregnancy application of ovulation-promoting drugs, or multiple embryo transfers with in vitro fertilization. Early pregnancy tends to be more severe and last longer; the uterine volume is significantly larger than that of a single pregnancy; late pregnancy, due to an excessively enlarged uterus, the diaphragm is raised, breathing is difficult, the stomach is full, walking difficulties, varicose veins and edema in the lower limb Wait for the symptoms of compression.

Multiple pregnancy test

1.B-ultrasound

Two fetal sacs can be seen in the first trimester; according to the sonograms of the fetal skull and spine in the second and third trimesters, the B ultrasound diagnostic compliance rate is 100%. Membrane diagnosis mainly depends on ultrasonography before 14 weeks of pregnancy: the gestational sacs are far apart in early pregnancy. If there is an amnion cavity in each of the gestational sacs, it is double chorion and double amniotic twin. "" or "double-peak" signs at the junctions are double chorion. A single chorionic twin amnion twin is observed when two amniotic cavities are observed in one pregnancy sac, or two yolk sacs are simultaneously displayed in one chorionic cavity. If only one yolk sac is shown in one chorionic cavity, it is a single chorion and single amniotic twin. Twins with different fetal sex in the second trimester are usually twin chorion (diploid twins). Chorionic diagnosis in early pregnancy is very important for perinatal care in the future.

2. Doppler ultrasound

Two fetal heart sounds with different frequencies are heard after 12 weeks of pregnancy.

3. Obstetric examination

Twins should be considered if: the uterus is greater than the gestational week; multiple limbs and two or more fetal heads are touched in the abdomen in the middle and late stages of pregnancy; the uterus is larger, the fetal head is smaller and disproportionate; heard in different parts Two fetal heartbeats with different frequencies, or listening to the fetal heart rate while counting for 1 minute, the two sounds differ by 10 times or more.

Multiple pregnancy diagnosis

Diagnosis can be made by combining clinical symptoms with imaging and obstetric examinations.

Multiple pregnancy complications

Complications during pregnancy

(1) Anemia twin pregnant women require increased iron and folic acid, and their plasma volume is significantly increased compared to single pregnancy, which causes relative blood dilution and anemia. Twin pregnancy is associated with anemia that is 2.4 times that of single pregnancy. Anemia during pregnancy can cause adverse effects on pregnant women and fetuses, such as anemia heart disease, pregnancy-induced hypertension, fetal growth retardation, intrauterine distress, postpartum hemorrhage, and postpartum infections.

(2) Preeclampsia twin pregnancy complicated with hypertension during pregnancy is up to 40%, which is 4 times that of single pregnancy. It often occurs early and is more serious. As the blood volume of pregnant women with multiple pregnancy increases, uterine tension is large, and complications such as placental abruption and pregnant women's heart failure are more likely to occur.

(3) The incidence of polyhydramnios in oligohydramnios twins is about 10%, of which monozygotic twins are 4 times higher than twins. In the presence of polyhydramnios, attention should be paid to the exclusion of neurological and fetal digestive tract malformations.

2. Complications during childbirth

Simple twin pregnancy is not an indication of cesarean delivery. You can choose a delivery method under the guidance of a doctor based on individual circumstances. But twin pregnancy is prone to the following complications:

(1) Twin pregnancy due to excessive uterine enlargement, excessive extension of uterine muscle fibers, prolonged labor during uterine contraction during labor, and prone to postpartum hemorrhage;

(2) When combined with excessive amniotic fluid, premature rupture of membranes and prolapse of umbilical cord are prone to occur due to increased intrauterine pressure;

(3) In a twin pregnancy, each fetus is usually smaller than a single fetus, which is prone to abnormal fetal position. After the first fetus is delivered, the second fetus has a large range of motion and is easy to turn into a horizontal position.

(4) During delivery, when the first fetus is delivered, the volume of the uterine cavity suddenly decreases, and the placenta attachment surface suddenly decreases. Therefore, placental abruption may occur, directly threatening the life of the second fetus and the safety of the mother;

(5) When the first fetus is delivered in the breech position and the second fetus is delivered in the head position, the first fetal head has not yet been delivered, and the second fetal head has fallen into the pelvic cavity. Neck interlocking causes dystocia, but it is rare in the clinic.

The above situation mostly occurs in a small fetus with a large pelvic cavity, or a single amniotic sac twin or a second premature rupture of the fetal membrane.

3. Perinatal complications

Perinatal mortality in twin pregnancy is higher, which is related to premature birth, fetal growth restriction, fetal malformation, and umbilical cord abnormalities. Single chorionic twin pregnancy has the risk of its special complications, such as twin transfusion syndrome, loss of twins, and reversal of arterial perfusion.

(1) Vascular anastomosis of twin placenta in twin transfusion syndrome : Anastomosis rate of blood vessels in single chorionic twin placenta is as high as 85% to 100%. There are three types of anastomotic, intervenous and arteriovenous anastomosis. The superficial part of the fetal surface of the placenta is mostly anastomosed, and a few are anastomosed. There is a difference in blood pressure between arterial-venous anastomosis of the placenta lobules deep in the placental tissue. Twin blood transfusion syndrome (TTTS) occurs in approximately 15% of single chorionic multiple pregnancy. The fetus of the recipient showed increased circulating blood volume, excessive amniotic fluid, enlarged heart or heart failure accompanied by edema; while the donor's circulating blood volume decreased, oligohydramnios, and growth restriction. Without intervention, the fatality rate for severe twin transfusion syndrome is as high as 80% to 100%.

(2) The death of one of the twins in the early pregnancy, such as the occurrence of one twin, has not been found to have any impact on the survivors. However, if a fetal death occurs in the second trimester of pregnancy, it may lead to the occurrence of late abortion, 90% of which occurs within 3 weeks. It should be reminded that the increased risk of intrauterine fetal death in surviving fetuses in late pregnancy during clinical observation may be related to abnormal placental thrombosis that affects placental function, so intensive monitoring is needed. In double chorionic twins, the prognosis of survivors is mainly affected by the gestational week; whereas in single chorionic twins, the intrauterine death of one fetus and the risk of intrauterine death of the other fetus are about 20%. The risk is about 25%.

(3) Reversal of arterial perfusion (no cardiac malformation) is a complication of single chorionic twin pregnancy. Cardiac arrest in one fetus, and partial blood perfusion from the cardiovascular system of the other fetus. The incidence of this condition is very low, but the risk of fetal death is high due to the intrauterine heart failure of the recipient's fetus. Umbilical cord ligation is usually used to separate the twins.

(4) Inconsistent twin growth means that the weight difference between two fetuses in the same pregnancy is 20%. It may be related to placental factors (abnormal placental development such as too small, etc.), chromosomal abnormalities, and twin blood transfusion syndrome, etc., 4% of which are due to fetal gender inconsistencies.

(5) Complete hydatidiform mole and coexisting fetus , that is, one fetus with a normal placenta, and the other a complete hydatidiform mole. About 60% of twin women with complete hydatidiform moles and normal fetuses will need chemotherapy for persistent trophoblastic tumors. There is no ideal treatment method, but serum HCG and respiratory symptoms of pregnant women should be monitored. ^[1]

Multiple Pregnancy Treatment

Treatment during pregnancy

(1) Periodic prenatal check-ups. Twin pregnancy is a high-risk pregnancy. Maternal and child outcomes are closely related to health care during pregnancy. Once diagnosed, health care and management should be done, nutrition should be strengthened, and sufficient protein, iron, vitamins, folic acid, Calcium and so on. Try to avoid overwork. After 30 weeks of pregnancy should be more bed rest, actively prevent pregnancy complications and avoid the occurrence of premature birth. Ultrasound monitoring of fetal growth and development.

(2) If one of the fetuses died in early pregnancy, the stillbirth can be fully absorbed. The fetus that died at 3 months of pregnancy is oppressed into a paper-like child and does not need to be treated; death in the third trimester usually does not cause maternal damage, but if there is a small amount of blood The release of enzymes to the mother will cause intravascular coagulation, and maternal coagulation function should be monitored.

(3) Twin blood transfusion syndrome is divided into five stages according to the ultrasound diagnosis, and dynamic observation can be taken in stage I, and selective fetal reduction, fetal microscopy placental vascular branch coagulation, and umbilical cord coagulation can be taken according to the situation. Or ligation, amniotic fluid reduction, amniotic membrane ostomy and so on. Among them, laser blocking the placenta blood vessel branch under fetal microscope is recognized as an effective treatment. But also need to pay attention to the complications after intrauterine fetal treatment.

2. Management during childbirth

Most twin pregnancy can be delivered by vagina, and it is necessary to make emergency equipment for blood transfusion, infusion and rescue of pregnant women, and proficient in newborn rescue and resuscitation technology.

(1) Indications for termination of pregnancy Complicated with acute polyhydramnios, causing symptoms of compression, such as dyspnea, severe discomfort, etc .; Maternal complications such as preeclampsia or eclampsia, when pregnancy is not allowed; fetus Deformity; has reached the due date has not yet labored, placental function is gradually reduced or amniotic fluid decreased.

(2) The choice of delivery method is based on the age, parity, gestational age, fetal exposure, history of infertility, and obstetric complications / complications. In principle, a trial of vaginal birth and appropriate relaxation of cesarean section indications. Vaginal trial production: Choose twins with the head exposed or the first fetus as the head position, the second fetus as the hip position, and the total weight of the two fetuses between 5000 and 5500g, and the weight of the second fetus should not exceed the first fetus. One fetus is 200 to 300 g. Indications for cesarean delivery: first fetal exposure, such as shoulder first exposure, buttock first exposure; weak uterine contraction leads to prolonged labor and poor treatment; fetal distress cannot be delivered via vagina for a short time. Severe complications require immediate termination of pregnancy, such as those with preeclampsia, placental abruption, or umbilical cord prolapse; those with conjoint deformity who cannot deliver vaginal birth.

3. Processing during labor

Pay attention to the uterine contractions during labor and the progress of labor and changes in the fetal heart rate. If uterine contraction weakness occurs, low concentrations of oxytocin can be given slowly. When the first fetus is delivered, it is immediately clamped at the end of the placental side umbilical cord to prevent blood loss in the second fetus. At the same time, the assistant fixed the second fetus in the abdomen in the abdomen and listened to the fetal heart. If there is no vaginal bleeding and the fetal heart is normal, waiting for natural delivery, usually the second fetus can be delivered in about 20 minutes. If there is no contraction after waiting for 10 minutes, artificial rupture of the membrane or low concentration of oxytocin can be given to promote uterine contraction. If umbilical cord prolapse or suspicious placental abruption or abnormal fetal heartbeat is found, immediately use forceps or gluteal traction to give birth as soon as possible.

4. Prevention and treatment of postpartum hemorrhage

Open the venous channel during delivery to prepare for infusion and blood transfusion; give oxytocin to promote uterine contraction immediately after delivery of the second fetus; closely observe the uterine contraction and vaginal bleeding after delivery, especially pay attention to the delayed bleeding within 2 to 4 hours after delivery. Antibiotics prevent infection if necessary. ^[2]

references:

1. Yuan Pengbo, Wei Wei, Yao Ying, Yang Lingling, Zhao Yangyu, Qiao Jie. Clinical analysis of assisted reproductive technology and pregnancy outcome of natural conception twins: Chinese Journal of Eugenics and Genetics, 2010 (18): 107-109.

2.ZHAOYang-yu, XIONGGuang-wu, MACai-hong, WEIYuan, WANGLi-naandQIAOJie. pplicationoffetoscopyinthemanagementofmonochorionicmultiplepregnancies: Chinese Medical Journal, 2010: 123 (1): 105-107.